The Inductive Effect of Neighboring Cations in Tuning Luminescence Properties of the Solid Solution Phosphors

Forming solid solutions through cation substitution is an efficient way to improve the luminescence properties of Ce³⁺ or Eu²⁺ activated phosphors and even to develop new ones, which is badly needed for phosphor-converted white LEDs. Here, we report new color tunable solid solution phosphors based on Eu²⁺ activated K₂Al₂B₂O₇ as a typical case to demonstrate that, besides crystal field splitting of 5d levels, centroid shift and Stokes shift can be dominant in tuning excitation and emission spectra as well as thermal stability of solid solution phosphors, both of which were previously considered to be negligible. Moreover, a general model involving the inductive effect of neighboring cations is proposed to explain the obvious variations in centroid shift and Stokes shift with cation substitution. Our work is propitious for the construction of more reasonable structure-property relations and thus offers theoretical guidance for designing solid solution phosphors.